Bone cement mixing and delivery device for injection and method thereof

ABSTRACT

A bone cement mixing and delivery assembly is disclosed for mixing a powdered copolymer and a liquid monomer to form a bone cement and delivering the bone cement. The assembly includes a cartridge having a distal end and a proximal end and defining a mixing chamber between the distal end and the proximal end. A transfer mechanism having a cap and a stem supporting a piston and a plunger is connected to the distal end. The transfer mechanism includes a first advancement mechanism for advancing the piston and plunger in unison and a second advancement mechanism for moving the plunger independent of the piston. The assembly further includes a removable handle having a shaft for attachment of a mixing blade and a quick-release connector and a release button for locking and unlocking the mixing blade from the removable handle.

FIELD OF THE INVENTION

[0001] The present invention relates generally to a bone cement deliveryassembly, one that is particularly suited for mixing a powderedcopolymer and a liquid monomer to form a bone cement and delivering thebone cement.

BACKGROUND OF THE INVENTION

[0002] In many surgical procedures, particularly orthopedic procedures,it is common practice to affix a prosthesis to a bone or joint structurefor improving the strength, rigidity and movement of the bone/jointstructure. Such prosthetic devices have been widely used, hip joints andknee joints are the most common examples of areas where prostheticdevices are used to reduce or eliminate pain and suffering that existsfrom typical leg movements.

[0003] As part of these surgical procedures, it has become commonpractice to secure the prosthesis to the bone or joint using a cementformed by mixing a polymer powder and a liquid monomer. The twocomponents must be thoroughly blended together to achieve the requiredconsistency for the fully mixed cement. The fully mixed cement is thenloaded into a separate dispensing apparatus for placement in the desiredarea and affixing of the prosthesis to the desired site.

[0004] Other uses of bone cement include repairing or mending bonefractures or shattered bone occurring from extreme trauma. Bone cementmay also be used during cosmetic or dental surgery. Moreover, bonecement may be used as a drug delivery or release system, whereby thebone cement is mixed with antibiotics or other desired drugs and appliedto a specific surgical site such that the drugs leach out and aredelivered directly to the surgical site. Some bone cements are alsodesigned to be absorbed by the body over time.

[0005] Because of the necessity for a fairly quick setting material, thecement is almost universally prepared by a surgical assistant during thecourse of the operation in the sterile operating room. Conventional bonecements are generally polymeric materials which are prepared bycopolymerization of the components as needed. Bone cement is prepared bycopolymerizng the liquid monomer and the powdered copolymer, such asmethyl methacrylate and polymethyl methacrylate or methyl methacrylatestyrene. In order to provide a bone cement having the desiredproperties, the compounds must be uniformly and thoroughly mixed so thata homogeneous reaction product is produced.

[0006] During the mixing and subsequent chemical reaction various vaporsare produced. Due to the noxious and toxic nature of such vapors, it ishighly undesirable to be exposed to them, particularly for extendedperiods of time in the course of multiple preparations. Since it isnecessary that the mixing be carried out for extended periods of time toensure a uniform reaction product and a minimum of concentration ofvolatile reactants, the period of exposure to harmful vapors can besubstantial. Moreover, during the mixing of the constituent componentsof the cement, air bubbles may be formed within the cement.

[0007] Most often, the two components forming the cement are mixed in amixing vessel and, once fully mixed, the cement is manually transferredfrom the mixing vessel to a dispensing member of a dispensing device.Typically, devices similar to caulking guns are employed for dispensingthe fully mixed cement to the desired location in the patient. Thesedevices have a piston which allows the bone cement to remain in thedispensing member.

[0008] In some other prior art systems, the cement is mixed in onevessel which is then directly connected to a feeding system that enablesthe mixed cement to be added to a holding tube for use with thedispensing device. The dispensing system, however, is separate andexposes the mixed cement to the surrounding personnel. Furthermore, caremust be exercised during the transfer of the mixed cement to thedispenser to avoid introducing air into the cement or to avoid dropping,spilling, or contaminating the cement.

[0009] Other prior art systems utilize a handle that operates mixingpaddles in a closed cylinder for combining the cement constituents. Uponmixing the bone cement, the handle must be removed. Conventional systemsincorporate frangible handles that when broken may produce fragmentsthat could contaminate the bone cement.

[0010] One such device is disclosed in U.S. Pat. No. 5,551,778 to Haukeet al. The '778 patent discloses a device having a mixing cylinder and amixing plunger extending therethrough. The standard powder and liquidcomponents are introduced into the chamber to form a bone cement and themixing plunger mixes the two components. The mixing plunger has apredetermined break point for breaking the mixing plunger and allowingfor its removal from the mixing cylinder. A discharge nozzle is thenconnected to the mixing cylinder and the mixing chamber is connected toa drive mechanism. The drive mechanism includes a discharge plunger thatis passed through the mixing cylinder forcing the bone cement from themixing cylinder out the nozzle. A portion of the bone cement remains inthe discharge nozzle and thus the system does not ensure completedelivery of the bone cement into the patient.

[0011] Another such device is disclosed in U.S. Pat. No. 5,879,116 toBarker et al. The '116 patent discloses a device having a mixing chamberintegral with a delivery chamber. The bone cement components areintroduced into the mixing chamber and a paddle having a handleextending from the mixing chamber is utilized to mix the components andform the bone cement. Once the components are adequately mixed, apassage way is opened between the mixing chamber and the deliverychamber. The handle is actuated causing rotation of the paddle and of anauger disposed within the delivery chamber. The paddle transfers thebone cement from the mixing chamber to the auger. The auger has threads,which taper away from the mixing chamber for pulling the bone cementfrom the mixing chamber into the delivery chamber. One disadvantage ofthis system is that the bone cement must have a relatively low viscosityto be pulled by the auger into the delivery chamber. Additionally, thebone cement may remain on the walls of the mixing chamber where thepaddle is unable to reach it.

[0012] Accordingly, it would be advantageous to provide a bone cementmixing and delivery assembly that includes a mechanism to transfer allof the bone cement from a mixing chamber to an delivery cartridge and todeliver all of the bone cement from the delivery cartridge into thepatient.

SUMMARY OF THE INVENTION AND ADVANTAGES

[0013] The present invention provides a bone cement mixing and deliveryassembly for mixing a powdered copolymer and a liquid monomer to form abone cement and delivering the bone cement. The device includes acartridge having a distal end and a proximal end defining a mixingchamber between the distal end and the proximal end. A lid is connectedto the proximal end and has an aperture. A transfer mechanism isconnected to the distal end and in sealing engagement with thecartridge. A piston is connected to the transfer mechanism such thatmovement of the transfer mechanism extends the piston through the mixingchamber for transferring the bone cement from the mixing chamber to theproximal end. The device is characterized by a plunger extending fromthe piston for forcing the bone cement through the aperture anddelivering the bone cement to the patient.

[0014] Accordingly, the subject invention proves a method comprising thesteps of filling a chamber having a proximal end with the bone cement,advancing a piston and a plunger in unison within the chamber fortransferring the bone cement out of an aperture in the proximal end ofthe chamber, and the method is characterized by advancing the plungerindependently of the piston to extend the plunger beyond the piston andinto the aperture.

[0015] The subject invention provides many advantages over conventionalsystems. First, the bone cement is mixed and dispensed from the samecontainer, thus eliminating the need to manually transfer the bonecement from a mixing vessel to a dispensing device. In addition, theremovable handle is released rather than broken off. Thus, cost isreduced, handling is minimized and the introduction of contaminants intothe mixture is minimized or eliminated. Furthermore, the compound is notexposed to air, thereby reducing or eliminating exposure of noxious andtoxic vapors to surrounding personnel during the surgical operation.Another advantage of the subject invention is that the compound is mixedin an environment evacuated by a vacuum. Thus, the formation of airbubbles is minimized, providing a uniform reaction product and, in turn,producing a stronger bone cement compound.

[0016] Additionally, the device of the subject invention provides amechanism for transferring all of the bone cement from the mixingchamber to the patient.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Other advantages of the present invention will be readilyappreciated as the same becomes better understood by reference to thefollowing detailed description when considered in connection with theaccompanying drawings wherein:

[0018]FIG. 1 is a perspective view of a first embodiment of a cementmixing and delivery assembly having a transfer mechanism and a removablehandle designed according to the present invention;

[0019]FIG. 2 is an exploded perspective view of the embodiment of FIG.1;

[0020]FIG. 3 is a cross-sectional view of a lid with an aperture havingthe removable handle extending therethrough designed according to thepresent invention;

[0021]FIG. 4 is a cross-sectional view of the embodiment of FIG. 1 shownin a mixing phase;

[0022]FIG. 5 is an exploded perspective view of the embodiment of FIG. 1shown in a delivery phase;

[0023]FIG. 6 is a cross-sectional view of the embodiment of FIG. 1 shownat the start of the transfer stage;

[0024]FIG. 7 is a cross-sectional view of the embodiment of FIG. 1 shownafter complete delivery of the bone cement;

[0025]FIG. 8 is a perspective view of the lid;

[0026]FIG. 9 is a perspective view of the transfer mechanism;

[0027]FIG. 10 is a perspective view of a mixing blade designed accordingto the present invention;

[0028]FIG. 11 is a bottom-side prespective view of a piston designedaccording to the present invention;

[0029]FIG. 12 is a top-side prespective view of the piston designedaccording to the present invention;

[0030]FIG. 13 is a perspective view of a cartridge designed according tothe present invention;

[0031]FIG. 14 is a perspective view of a plunger designed according tothe present invention;

[0032]FIG. 15 is a perspective view of a shaft designed according to thepresent invention;

[0033]FIG. 16 is a perspective view of a delivery cartridge designedaccording to the present invention;

[0034]FIG. 17 is a cross-sectional view of a second embodiment of acement mixing and delivery assembly designed according to the presentinvention;

[0035]FIG. 18 is a cross-sectional view of a third embodiment of acement mixing and delivery assembly designed according to the presentinvention;

[0036]FIG. 19 is a cross-sectional view of a fourth embodiment of acement mixing and delivery assembly having multiple plungers anddesigned according to the present invention;

[0037]FIG. 20A is a perspective view of a fifth embodiment of a cementmixing and delivery device designed according to the present invention;

[0038]FIG. 20B is a cross-sectional view of the cement mixing anddelivery device of FIG. 20A;

[0039]FIG. 21A is a perspective view of a sixth embodiment of a cementmixing and delivery device designed according to the present invention;

[0040]FIG. 21B is a cross-sectional view of the cement mixing anddelivery device of FIG. 21A;

[0041]FIG. 22 is a cross-section view of a seventh embodiment of acement mixing and delivery device designed according to the presentinvention; and

[0042]FIG. 23 is a perspective view of an alternate embodiment for aremovable handle.

DETAILED DESCRIPTION OF THE INVENTION

[0043] Referring to the Figures, wherein like numerals indicate like orcorresponding parts throughout the several views, a bone cement mixingand delivery assembly for mixing a powdered copolymer and a liquidmonomer to form a bone cement and delivering the bone cement is showngenerally at 30. In one embodiment, delivery of the bone cement isperformed percutaneously. Percutaneous, as used in the medical field,relates to passing or effectuating the bone cement through the skin. Themixing and delivery assembly 30 functions in three phases comprising amixing phase, a transfer phase, and a delivery phase. All phases aredescribed in detail below with the transfer and delivery phasesdescribed first, followed by the mixing phase. Specifically, FIGS. 5-7and FIGS. 17-21 show the assembly 30 during the transfer and deliveryphases. FIGS. 1-4 illustrate the assembly 30 during the mixing phase.

[0044] The mixing and delivery assembly 30 includes a cartridge 32(shown separately in FIG. 13) having a distal end 34 and a proximal end36 and defining a chamber 38 between the distal end 34 and the proximalend 36, as shown in FIGS. 4, 6, and 13. An external portion of thecartridge 32 adjacent the distal end 34 further includes male threads42. In the preferred embodiment, the chamber 38 is a mixing chamber 40for receiving the liquid monomer and the powdered copolymer to form thebone cement. The chamber 38 may, however, receive premixed bone cement,in which case the assembly 30 is used only to deliver the premixed bonecement to the patient. Alternatively, the chamber 38 may be packagedwith the powdered copolymer. Thus, prior to use, only the liquid monomeris added.

[0045] A lid 44 is connected to the proximal end 36 and it has a firstaperture 46. The lid 44 sealingly engages the proximal end 36. In thepreferred embodiment, the lid 44 has threads for engaging correspondingthreads on the proximal end 36 as shown in FIGS. 2-7. The lid 44 alsohas a vent 48 connected to the lid 44 for allowing a vacuum (not shown)to be attached to the vent 48 with a vacuum attachment 76 for removinggas particles from the chamber 38. The vacuum may be any device capableof applying a pressure differential, as is known in the art, forremoving gas particles from the mixing chamber 40. Removal of the gascreates a stronger cement. Also the vacuum assists in the removal ofobnoxious and potentially harmful gases produced during mixing. A filter50 may also be disposed within the vent 48 for filtering the gasparticles.

[0046] The mixing and delivery assembly 30 may further include a coolingchamber 52 positioned adjacent the mixing chamber 40 for receiving acooling fluid (not shown) to cool the mixing chamber 40. The coolingchamber 52 is capable of receiving any cooling fluid as is known in theart. As the liquid monomer and powder copolymer are mixed, an exothermicchemical reaction occurs. Illustrative examples of such a cooling fluidinclude ice inserted into the cooling chamber 52 or chemicals whichproduce an endothermic reaction for cooling the chamber 38. Alternately,the cooling chamber 52 could be annular and connected to a cold air orwater supply for passing cold air or water through the cooling chamber52. The bone cement remains useable for a longer period of time if theheat from the exothermic reaction is dissipated.

[0047] A transfer mechanism 54 threads onto the distal end 34, as shownin FIGS. 1, 2, 4-7, and 17-21. The transfer mechanism 54 includes a cap56. The cap 56 has female threads 58 for engaging the male threads 42 ofthe distal end 34. The cap 56, as shown in FIG. 9, further includes astem 62 extending from the cap 56. A piston 64 is rotatably supported bythe stem 62 and housed within the cartridge 32. The piston 64 has aperimeter which extends to an inner wall of the chamber 38. The piston64 is shown separately in FIGS. 11 and 12. The piston 64 also has apiston seal 65 between the piston 64 and the chamber 38 for preventingbone cement from flowing therebetween. Preferably, the piston seal 65comprises an O-ring.

[0048] The transfer mechanism 54 has a first advancement mechanism 68and a second advancement mechanism 70. The first advancement mechanism54 is for use in the transfer phase to advance the piston 64 through thechamber 38 and transfer the bone cement from the chamber 38 and out theaperture 46. The first advancement mechanism 68 includes a pin system 72interconnecting the piston 64 and the stem 62 for preventing rotation ofthe piston 64 relative to the stem 62 until the piston 64 reaches a stopposition 74, shown in FIG. 6. The stop position 74 is defined by achannel 66 in the chamber 38 being adjacent the piston 64. The firstadvancement mechanism 68 further includes a disconnect system 78disconnecting the female threads 58 from the male threads 42, as shownin FIG. 7. After the female threads 58 and the male threads 42 aredisconnected, the cap 56 can be rotated relative to the cartridge 32without moving or rotating the piston 64.

[0049] In the preferred embodiment, the female threads 58 are formed asa plurality of circumferential segments 60. The plurality ofcircumferential segments 60 are connected to the transfer mechanism 54to move axially along the male threads 42 thereby advancing the piston64. The cartridge 32 includes an annular recess 82 adjacent the malethreads 42. A first biasing device 84 moves the segments into theannular recess 82 once the piston 64 reaches the stop position 74.Preferably, the circumferential segments 60 are divided into sectionsand each section has a nipple 86 for engaging the first biasing device84, as shown in FIG. 2. Additionally, the plurality of circumferentialsegments 60 may only encircle a portion of the threaded portion 40.Preferably, the first biasing device 84 is a metal spring band whichcollapses the plurality of circumferential segments 60 into the annularrecess 82. As the circumferential segments 60 reach the end of the malethreads 42, the first biasing device 84 forces the plurality ofcircumferential segments 60 into the annular recess 82. As thecircumferential segments 60 are forced into the annular recess 82, thecircumferential segments 60 disengage from the transfer mechanism 54which disconnects from the piston 64. When the circumferential segments60 have entered the annular recess 82, the transfer stage is completedand the bone cement has been transferred from the chamber 38 and out theaperture 46. The first biasing device 84 and the annular recess 82prevent the first advancement mechanism 68 from being able to back downthe threaded portion 42. In other words, the first biasing device 84allows the mixing and delivery assembly 30 to be used for a singleapplication.

[0050] The assembly 30 also includes a plunger 88 movable relative tothe piston 64 for extending from the piston 64 and into the aperture 46for forcing the bone cement through the aperture 46. The extending ofthe plunger 88 from the piston 64 through the aperture 46 is thebeginning of the delivery phase. The plunger 88 has a groove 90 and thestem 62 has a tongue 92 for interconnecting the plunger 88 to the stem62. The interconnection of the tongue 92 and the groove 90 allows theplunger 88 to rotate with the stem 62 and to move axially relative tothe stem 62 in the delivery phase via threaded interaction between theplunger 88 and the piston 64.

[0051] The pin system 72 includes a pin 94 disposed radially tointerconnect the stem 62 and the piston 64. The pin 94 has a head 95 anda tail 97 and the head 95 is larger than the tail 97. A second biasingdevice 96, comprising a spring around the tail 97, urges the pin 94radially outwardly against the cartridge 32. The cartridge 32 has thechannel 66 adjacent the proximal end 36 for receiving the head 95. Asthe first advancement mechanism 68 moves the piston 64 through thechamber 38, the spring is compressed due to the head 95 engaging theinner wall of the chamber 38. When the piston 64 reaches the stopposition 74, the pin 94 is received by the channel 66 and the springforces the pin 94 outward. Once this happens, the pin 94 no longerengages the stem 65 and only engages the chamber 38 and the piston 64.

[0052] The second advancement mechanism 70 includes threads 100 on theplunger 88 that engage threads 101 inside the piston 64. The secondadvancement mechanism 70 advances the plunger 88 from the piston 64during the delivery phase. A plunger seal 103 is disposed between theplunger 88 and the piston 64 to prevent bone cement from flowingtherebetween during the mixing and transfer phases. The tongue 92 andthe groove 90 impart the continued rotation of the cap 56 to the plunger88. The plunger 88 thereafter threadably engages the piston 64 such thatthe plunger 88 extends from the piston 64. Once the piston 64 hasreached the stop position 74, the plunger 88 moves independently of thepiston 64 and the piston 64 acts as a nut as the cap 56 is rotated.

[0053] Alternately, and as shown in FIGS. 17 and 18, the secondadvancement mechanism 70 may include a rack 102 connected to the plunger88 and a gear 104 engaging the rack 102 to advance the plunger 88 duringthe delivery phase. The gear 104 may be either a pinion gear 106 (FIG.17) or a worm gear 108 (FIG. 18). A rod 110 is connected to the gear 104and extends through the transfer mechanism 54 for actuating the gear 104manually or by a drive (not shown). The rod 110 is rotated causing thegear 104 to rotate causing the rack 102 to move linearly. Movement ofthe rack 102 extends the plunger 88 from the piston 64 and continues todeliver the bone cement through the aperture 46.

[0054] The assembly 30 further includes a delivery cartridge 112 havinga cartridge end 114 connected to the aperture 46 of the lid 44 andextending to an open end 116. The delivery cartridge 112 (shownseparately in FIG. 16) has a smaller diameter than the mixing chamber 40and the plunger 88 has a smaller cross-section which allows the plunger88 to extend through the aperture 46 and into the delivery cartridge112. As the delivery cartridge 112 receives the plunger 88, the bonecement is forced through the delivery cartridge 112. The deliverycartridge 112 may also include cooling chambers 52 as discussed abovefor surrounding the mixing chamber 40. For example, a water-based gelmay be inserted into the cooling chamber 52 around the deliverycartridge 112 and cooled. The cooled delivery cartridge 112 allows thebone cement to be available for use for longer periods of time. Thedelivery cartridge 112 may be permanently or removably connected to thelid 44. Alternate embodiments may have the delivery cartridge 112connected to the opposite end of a removable handle 120.

[0055] The subject invention may also be utilized with more than onedelivery cartridge 112, as shown in FIG. 19. Multiple deliverycartridges 112 require a plurality of plungers 88 corresponding to eachof the delivery cartridges 112. For instance, two plungers 88 may extendfrom the piston 64. The plungers 88 would be configured as describedabove with each plunger 88 engaging the second advancement mechanism 70.Therefore, actuation of the second advancement mechanism 70 advancesboth plungers 88. Alternately, the plungers 88 could have individualsecond advancement mechanisms such as the worm gear 108 or pinion gear106 type of second advancement mechanisms 70. For percutaneous delivery,a flexible extension tube (not shown) is removable coupled to the openend 116. A needle having a handle (not shown) is coupled to theextension tube for injection through the skin and into the patient.

[0056] In one embodiment, the mixing and delivery assembly 30 alsoincludes at least one indicator 118 disposed on the transfer mechanism54 or rod 110 indicating an amount of the bone cement to be deliveredinto the patient upon rotation of the transfer mechanism 54 and thesecond advancement mechanism 70. For instance, the indicator 118 on thetransfer mechanism 54 may represent a quarter of a turn. The quarter ofa turn may further represent two cubic centimeters of bone cement to bedelivered into the patient. The indicators allow medical personnel toeasily and efficiently deliver predetermined amounts of the bone cementto the patient. In another embodiment, the delivery cartridge 112includes markings indicative of the amount of bone cement delivered.

[0057] The assembly 30 of the subject invention can be used with amethod of delivering the bone cement. The method includes the steps offilling the chamber 38 with the bone cement and sealing the chamber 38by connecting the lid 44 to the proximal end 36. The preferred methodincludes disposing the liquid monomer and the powdered copolymer intothe chamber and agitating the liquid monomer and the powdered copolymerto form the bone cement as described below. However, the subjectinvention is particularly useful with premixed bone cement. Once themixed bone cement is in chamber 38, the next step is actuating thetransfer mechanism 54 to advance the first advancement mechanism 68.Advancing the first advancement mechanism 68 includes advancing thepiston 64 and the plunger 88 in unison for transferring the bone cementfrom the chamber 38 to the proximal end 36. In the preferred embodiment,actuation of the first advancement mechanism 68 begins by rotating thetransfer mechanism 54. Rotation of the cap 56 causes the plurality ofcircumferential segments 60 to move along male threads 42. When theplurality of circumferential segments 60 reaches the annular recess 82,the first biasing device 84 forces the plurality of circumferentialsegments 60 radially inward and into the annular recess 82 therebyseparating the plurality of circumferential segments 60 from the cap 56.

[0058] The method is then characterized by actuating the secondadvancement mechanism 70 and advancing the plunger 88 independently ofthe piston 64 to extend the plunger 88 beyond the piston 64 therebydelivering the bone cement into the patient. Specifically, in apreferred embodiment, once the plurality of circumferential segments 60is recessed, the pin 94 engages the channel 66 in the mixing chamber 40which fixes the position of the piston 64. Continued rotation of the cap56 causes the plunger 88 to rotate within the piston 64 and extendtherefrom. The cap 56 is rotated until the plunger 88 has moved into thedelivery cartridge 112 to force the bone cement completely from themixing chamber 40.

[0059] In alternate embodiments, the second advancement mechanism 70 hasthe rod 110 extending from the cartridge 32 and engaging the gear 104.After the piston 64 is locked in place, the rod 110 is rotated causingthe plunger 88 to extend from the piston 64. Alternate aspects of theassembly 30, as described above, further include the steps of ventingthe chamber 38, removing gas particles from the chamber 38, andfiltering the gas particles as the gas particles are removed from thechamber 38.

[0060] The assembly 30 preferably is further used to mix the liquidmonomer and powder copolymer in the mixing chamber 40, as shown in FIGS.1-4. In the mixing phase, the assembly 30 includes a removable handle120 extending through the aperture 46 and having a first end 122 and asecond end 124 defining a hollow cavity 126 therebetween. Otherembodiments may include the removable handle 120 extending through thecap 56. The removable handle 120 may also be used to move the plunger 88through the aperture 46. One such removable handle 120 is illustrated inFIG. 22. The removable handle 120 includes a pivot 121 for engaging acap stop 123. While in the transfer phase, the removable handle 120pivots and is at a right angle with the plunger 88. The removable handle120 can be used to rotate the cap 56 during this stage. During thedelivery phase, the removable handle 120 is pivoted and coextensive withsaid plunger 88. Rotation of the removable handle 120 extends theplunger 88 from the piston 64.

[0061] A mixing blade 128 (shown separately in FIG. 10) has a bore 130for receiving the first end 122 of the removable handle 120. The secondend 124 of the removable handle 120 allows a knob 132 to be attached forrotating and moving the mixing blade 128 through the mixing chamber 40.The mixing blade 128 may be any blade used for mixing, but is preferablya circular blade or a circular disc that is able to slide within themixing chamber 40. The mixing blade 128 has a circumference whichextends to the inner wall of the mixing chamber 40, while still allowingfor movement of the mixing blade 128. The mixing blade 128 may furtherinclude slots 134 for increasing the efficiency of the mixing. A shaft136 (shown separately in FIG. 15) is disposed within the hollow cavity126 and has a blade attachment end 138 with projections 140 extendingfrom the first end 122. A shaft seal 141 is disposed between the shaft136 and the removable handle 120 for preventing cement from flowingtherebetween.

[0062] A quick-release bayonet-type connector 142 is located between themixing blade 128 and the shaft 136 such that the mixing blade 128 isreleasably connected to the removable handle 120. A release button 144engages the shaft 136 and is movable between a locked position and anunlocked position. The quick-release connector 142 further includesflanges 146 extending inward from the bore 130 of the mixing blade 128and a pair of flange recesses 148 disposed within the first end 122 ofthe removable handle 120. In the unlocked position, the projections 140are offset from the flange recesses 148 such that the flange 146 can bereceived by the flange recess 148. Movement of the release button 144causes the shaft 136 to rotate while the removable handle 120 remainsstill. The shaft 136 rotates causing the projections 140 to engage theflanges 146 and force the flanges 146 into the flange recess 148. Oncethe release button 144 is in the locked position, the mixing blade 54 islocked to the removable handle 120. The removable handle 120 ismanipulated manually or by a motor (not shown) to move the mixing blade54 through the mixing chamber 40 and mix the cement components. Theremovable handle 120 is of sufficient length to extend the mixing blade128 through the entire length of the mixing chamber 40 and rotate themixing blade 128 to ensure complete mixing.

[0063] An alternate quick-release connector 142 is shown in FIG. 23. Acollapsible ball 143 is connected to the first end 122 of the removablehandle 120. When the release button 144 is in the unlocked position, thecollapsible ball 143 is collapsed and can be inserted into the bore 130.The release button 143 is moved to the locked position and thecollapsible ball 143 engages the bore 130 thereby locking the mixingblade 128 to the removable handle 120.

[0064] The assembly 30, as utilized in the mixing phase, includes amethod of mixing the powdered copolymer and the liquid monomer to formthe bone cement. The method includes the steps of disposing the powderedcopolymer and the liquid monomer into the mixing chamber 40 andconnecting the lid 44 to the proximal end 36 to seal the mixing chamber40 having the mixing blade 128 disposed within the mixing chamber 40.Preferably, the removable handle 120 is inserted through the aperture 46of the lid 44 while the lid 44 is not connected to the cartridge 32.However, the quick-release connector 142 allows for the mixing blade 128to be initially within the mixing chamber 40 and the lid 44 attachedwhen inserting the removable handle 120 through the aperture 46.Additionally, the two components may be added with the lid 44 alreadyconnected and the mixing blade 128 disposed within the mixing chamber40. The removable handle 120 is manipulated moving the mixing blade 128and agitating the powdered copolymer and the liquid monomer to form thebone cement. As the components are mixed together, a chemical reactionensues, producing a gas that may be harmful if inhaled by the medicalpersonnel. The vacuum is applied to the vent 48 to remove gas particlesfrom the mixing chamber 40 preventing the gas from being inhaled. Theremoval of the gas also ensures that the bone cement will be formedwithout gas bubbles providing a stronger cement. Additionally, thefilter 50 may be utilized for filtering the gas particles as the gasparticles are being removed from the mixing chamber 40.

[0065] Once mixing is complete, the release button 144 is moved to theunlocked position thereby releasing the mixing blade 128 from thequick-release connector 142 such that the removable handle 120 isremovable through the aperture 46 and the mixing blade 128 remains inthe mixing chamber 40. When the release button 144 is moved to theunlocked position, the shaft 136 is rotated causing the projections 140of the blade attachment end 138 to be offset from the flanges 146 of thebore 130. The removable handle 120 is then removed from the bore 130 ofthe mixing blade 128 and through the aperture 46. Since the mixing blade128 is released without having to break the removable handle 120, thebone cement does not become contaminated with fragments.

[0066]FIGS. 20A & B illustrate another embodiment of the cement mixingand delivery assembly 30. The first advancement mechanism 54 is actuatedby rotating the cap 56 to move the piston 64 through the mixing chamber40 along the male threads 42. The assembly 30 allows the removablehandle 120 to remain in the mixing chamber 40 while the secondadvancement mechanism 70 is operated. The second advancement mechanism70 includes the plunger 88 extending through the removable handle 120and through the mixing blade 128. The delivery cartridge 112 extendsfrom the lid 44 while the plunger 88 and the removable handle 120 extendthrough the cap 56. The second advancement mechanism 70 is actuated byforcing the plunger 88 through the delivery cartridge 112 to deliver thebone cement by applying a force to the knob 132 of the removable handle120. In this embodiment, the mixing blade 128 has tapered slots 134 toensure better mixing and to assist in transferring the bone cement.

[0067]FIGS. 21A & B illustrate yet another embodiment of the cementmixing and delivery assembly 30. The mixing handle 120 and the deliverycartridge 112 both extend from the lid 44. The first advancementmechanism 54 is actuated by rotating the cap 56 to move the piston 64through the mixing chamber 40 along the male threads 42. The secondadvancement mechanism 70 includes the rod 110 extending from thecartridge 32 and the gear 104 engaging the plunger 88. When the rod 110is rotated, the plunger 88 moves linearly through the mixing blade 128and through the delivery cartridge 112 to deliver the bone cement.

[0068] Obviously, many modifications and variations of the presentinvention are in light of the above teachings. The invention may bepracticed otherwise specifically described within the scope of theappended claims.

What is claimed is:
 1. A bone cement mixing and delivery assembly fordelivering a bone cement, said assembly comprising: a cartridge having adistal end and a proximal end and defining a chamber between said distalend and said proximal end; a lid connected to said proximal end andhaving an aperture; a piston disposed in said chamber for transferringsaid bone cement from said chamber to said proximal end; a transfermechanism adjacent to said distal end and in sealing engagement withsaid cartridge, said transfer mechanism moving said piston through saidchamber, and a plunger extendable from said piston for forcing said bonecement through said aperture.
 2. An assembly as set forth in claim 1wherein said transfer mechanism includes a first advancement mechanismfor advancing said piston and said plunger in unison
 3. An assembly asset forth in claim 2 wherein said transfer mechanism includes a secondadvancement mechanism for advancing said plunger relative to saidpiston.
 4. An assembly as set forth in claim 3 further including ardelivery cartridge having a cartridge end connected to said aperture andextending to an open end with a smaller diameter than said chamber, saidplunger having a cross section permitting the plunger to extend throughsaid aperture and into said delivery cartridge.
 5. A bone cement mixingand delivery assembly for mixing a powdered copolymer and a liquidmonomer to form a bone cement and delivering the bone cement, saidassembly comprising: a cartridge having a distal end and a proximal endand defining a chamber between said distal end and said proximal end; alid connected to said proximal end and having an aperture; a pistondisposed in said chamber and presenting a face for transferring the bonecement from said chamber to said proximal end; a plunger moveablerelative to said piston for extending from said piston and into saidaperture for forcing the bone cement through said aperture; and atransfer mechanism connected to said distal end of said cartridge formoving said piston and said plunger in unison to a stop position thatlimits further movement of said piston and thereafter moves said plungerrelative to said piston and into said aperture.
 6. An assembly as setforth in claim 5 wherein said transfer mechanism includes a capsurrounding said distal end and a first advancement mechanisminterconnected between said cap and said distal end for moving saidpiston and said plunger in unison and a second advancement mechanism formoving said plunger relative to said piston.
 7. An assembly as set forthin claim 6 wherein said first advancement mechanism includes malethreads on said distal end and female threads inside said cap threadablyengaging said male threads for moving said cap axially over saidcartridge upon rotation of said cap relative to said cartridge.
 8. Anassembly as set forth in claim 6 wherein said second advancementmechanism includes coacting threads interconnecting said plunger andsaid piston for moving said plunger axially relative to said piston inresponse to rotation of said cap at said stop position.
 9. An assemblyas set forth in claim 7 wherein said second advancement mechanismincludes a rack on said plunger and a gear engaging said rack to movesaid plunger relative to said piston upon rotation of said gear.
 10. Anassembly as set forth in claim 7 wherein said cap includes a stem andsaid piston is rotatably supported on said stem, a pin systeminterconnecting said piston and said stem for preventing relativerotation between said piston and said stem until said piston moves tosaid stop position, said first advancement mechanism includes adisconnect system for disconnecting said female threads from said malethreads for allowing rotation of said cap relative to said cartridgewithout relative axial movement therebetween at said stop position. 11.An assembly as set forth in claim 10 wherein said disconnect systemincludes an annular recess in said cartridge adjacent said male threadsand a plurality of circumferential segments forming said female threadsand a first biasing device for moving said segments radially into saidannular recess at said stop position.
 12. An assembly as set forth inclaim 10 wherein said first advancement mechanism includes a tongue anda groove interconnecting said plunger and said stem for rotating saidplunger with said stem while allowing said plunger to move axiallyrelative to said stem.
 13. An assembly as set forth in claim 10 whereinsaid pin is disposed radially to interconnect said stem and said piston,a second biasing device for urging said pin out radially and intoengagement with said cartridge, said cartridge having a channel adjacentsaid proximal end for receiving said pin at said stop position toprevent rotation of said piston and thereby to cause axial movement ofsaid plunger relative to said piston in response to rotation of said capat said stop position.
 14. An assembly as set forth in claim 5 furthercomprising at least one indicator indicating an amount of the bonecement to be delivered upon rotation of said second advancementmechanism.
 15. An assembly as set forth in claim 5 further comprising avent connected to said lid for removing gas particles from said chamber.16. An assembly as set forth in claim 15 further comprising a filterdisposed within said vent for filtering said gas particles.
 17. Anassembly as set forth in claim 5 further comprising a cooling chamberpositioned adjacent said chamber for receiving a cooling fluid to coolsaid chamber.
 18. An assembly as set forth in claim 5 further comprisinga removable handle extending through said aperture and having a firstend and a second end.
 19. An assembly as set forth in claim 18 whereinsaid removable handle is coextensive with said plunger whereby actuationof said transfer mechanism extends said plunger from said piston.
 20. Anassembly as set forth in claim 19 further comprising a pivotinterconnecting said plunger and said removable handle for allowing saidremovable handle to extend at a right angle from said plunger.
 21. Anassembly as set forth in claim 20 further comprising a cap stopextending from said transfer mechanism and positioned for engagementwith said removable handle when said removable handle is positioned at aright angle to said plunger whereby said removable handle aids inrotation of said transfer mechanism.
 22. An assembly as set forth inclaim 18 further comprising a mixing blade releasably attached to saidremovable handle.
 23. An assembly as set forth in claim 22 furthercomprising a quick-release connector between said mixing blade and saidremovable handle.
 24. A method of delivering a bone cement from acartridge having a distal end and a proximal end defining a chambertherebetween and an aperture in the proximal end, said method comprisingthe steps of: filing a chamber having a proximal end with the bonecement; advancing a piston and a plunger in unison within the chamberfor transferring the bone cement out of an aperture in the proximal endof the chamber; and advancing the plunger independently of the piston toextend the plunger beyond the piston and into the aperture.
 25. A methodas set forth in claim 24 wherein the bone cement further includes aliquid monomer and a powdered copolymer and further including the stepof disposing the liquid monomer and the powdered copolymer into thechamber.
 26. A method as set forth in claim 25 further including thestep of agitating the liquid monomer and the powdered copolymer to formthe bone cement.
 27. A method set forth in claim 24 further includingthe step of venting the chamber and removing gas particles from thechamber.
 28. A method set forth in claim 27 further including the stepof filtering the gas particles as the gas particles are removed from thechamber.
 29. A bone cement mixing and delivery assembly for mixing apowdered copolymer with a liquid monomer to form a bone cement anddelivering the bone cement, said device comprising: a cartridge having adistal end and a proximal end and defining a mixing chamber between saiddistal end and said proximal end; a lid connected to said proximal endand having an aperture; a removable handle extending through saidaperture and having a first end and a second end defining a hollowcavity between said first end and said second end; a shaft disposedwithin said hollow cavity and extending from said first end of saidremovable handle; a mixing blade having a bore and said bore receivingsaid first end of said removable handle; and a quick-release connectorbetween said mixing blade and said shaft such that said mixing blade isreleasable from said removable handle.
 30. An assembly as set forth inclaim 29 wherein said quick-release connector further comprises arelease button engaging said shaft and being moveable between a lockedand an unlocked position for locking and unlocking said mixing blade tosaid removable handle.
 31. An assembly as set forth in claim 30 whereinsaid quick-release connector further comprises a flange extending fromsaid bore of said mixing blade and a flange recess disposed in saidfirst end of said removable handle such that in said unlocked positionsaid flange engages said flange recess.
 32. An assembly as set forth inclaim 31 wherein said shaft further comprises a blade attachment endextending through said bore, said blade attachment end having aprojection for engaging said flange wherein engagement of said flangeoccurs when said release button is in said locked position and saidflange is in said flange recess.
 33. An assembly as set forth in claim32 further including a piston disposed in said mixing chamber andpresenting a face for transferring the bone cement from said mixingchamber to said proximal end.
 34. An assembly as set forth in claim 33further including a plunger moveable relative to said piston forextending from said piston and into said aperture for forcing the bonecement through said aperture.
 35. An assembly as set forth in claim 34further including a transfer mechanism connected to said distal end ofsaid cartridge for moving said piston and said plunger in unison to astop position that limits further movement of said piston and thereaftermoves said plunger relative to said piston and into said aperture. 36.An assembly as set forth in claim 35 wherein said transfer mechanismincludes a cap surrounding said distal end and a first advancementmechanism interconnected between said cap and said distal end for movingsaid piston and said plunger in unison and a second advancementmechanism for moving said plunger relative to said piston.
 37. Anassembly as set forth in claim 36 wherein said first advancementmechanism includes male threads on said distal end and female threadsinside said cap threadably engaging said male threads for moving saidcap axially over said cartridge upon rotation of said cap relative tosaid cartridge.
 38. An assembly as set forth in claim 37 wherein saidsecond advancement mechanism includes coacting threads interconnectingsaid plunger and said piston for moving said plunger axially relative tosaid piston in response to rotation of said cap at said stop position.39. An assembly as set forth in claim 29 further comprising a ventconnected to said lid for removing gas particles from said mixingchamber.
 40. An assembly as set forth in claim 39 further comprising afilter disposed within said vent for filtering said gas particles. 41.An assembly as set forth in claim 29 further comprising a coolingchamber positioned adjacent said mixing chamber for receiving a coolingfluid to cool said mixing chamber.
 42. An assembly as set forth in claim30 wherein said quick-release connector further comprises a collapsibleball extending from said first end of said removable handle and engagingsaid mixing blade such that in said unlocked position said collapsibleball collapses thereby releasing said mixing blade.
 43. A method ofmixing a powdered copolymer and a liquid monomer to form a bone cementin a cartridge having a distal end and a proximal and defining a mixingchamber therebetween with a removable handle having a release button anda quick-release connector for attachment to a mixing blade and a lidhaving an aperture connected to the proximal end, said method comprisingthe steps of: disposing the powdered copolymer and the liquid monomerinto the mixing chamber; connecting the lid to the proximal end to sealthe mixing chamber having the mixing blade disposed within the mixingchamber; agitating the powdered copolymer and the liquid monomer withthe mixing blade by manipulating the removable handle to form the bonecement; and actuating the release button and releasing the mixing bladefrom the quick-release connector such that the removable handle isremovable through the aperture and the mixing blade remains in themixing chamber.
 44. A method as set forth in claim 43 wherein thequick-release connector further includes a shaft disposed within theremovable handle and connected to the release button and wherein thestep of actuating the release button further comprises the step ofsliding the release button and rotating the shaft to unlock the mixingblade from the removable handle.
 45. A method as set forth in claim 43wherein the step of connecting the lid further comprises the step ofinserting the removable handle through the aperture of the lid prior toconnecting the lid to the proximal end.
 46. A method as set forth inclaim 45 wherein the step of connecting the lid further comprises thestep of attaching the mixing blade to the shaft while the release buttonis in the unlocked position and sliding the release button to a lockedposition for locking the mixing blade to the removable handle such thatmixing blade is on one side of the lid, and it enters the mixing chamberas the lid is connected.
 47. A method as set forth in claim 43 furthercomprising the step of removing gas particles from the mixing chamber.48. A method as set forth in claim 47 further comprising the step offiltering the gas particles as the gas particles are being removed fromthe mixing chamber.